In image reading apparatuses such as a scanner, there is a demand for an increase in image reading speed. There is an apparatus includes plural document conveying paths, a reading sensor that reads a first surface image of an original document and a reading sensor that reads a second surface image of the original document is arranged in each of the conveying paths to increase speed for reading the images on both the surfaces of the original document. As such an image reading apparatus, for example, JP-A-2006-168972 discloses an apparatus including a first branch path for conveying an original document to a first reading position and a second branch path for conveying the original document to a second reading position. Further, for example, JP-A-2004-15299 discloses an apparatus that includes a scanner device and a CIS (Contact Image Sensor) provided across a first conveying path and reads, simultaneously using the scanner device and the CIS, both surfaces of an original document conveyed on the first conveying path.
However, both the apparatuses are not applicable to an increase in image reading speed in continuously reading original documents using the same reading sensor.
Therefore, there is a demand for an auto document feeding device that conveys, in continuously reading original documents with the same reading sensor, the original documents to an image reading position at high sped without damaging the original documents, realizes efficient document reading, and realizes an increase in image reading speed.